Pull request 1799: AG-21072-stats-conf-race

Merge in DNS/adguard-home from AG-21072-stats-conf-race to master

Squashed commit of the following:

commit 26843b70ab8bfe0fa110c4156f2fd3f53ec5ee74
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Apr 4 20:30:22 2023 +0300

    all: imp docs, locks

commit 942a5baa9606376dd06a3ef3284c17133014f768
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Apr 4 19:15:18 2023 +0300

    stats: fix conf races

internal/querylog/querylog.go

@@ -33,6 +33,8 @@ type QueryLog interface {
 }
 
 // Config is the query log configuration structure.
+//
+// Do not alter any fields of this structure after using it.
 type Config struct {
 	// Ignored is the list of host names, which should not be written to log.
 	Ignored *stringutil.Set